How Does Air And Air Pressure Affect The Weather?

"Weather" is the name we give to the (local) optical, thermal, and precipitation effects occurring in an air mass at any given time. Without air, there is no weather.

Differences in air pressure make the air move. Without air pressure changes, weather gets pretty dull. (Where I live, a temperature inversion and stagnant air can last quite some time if a high pressure area comes to rest.) Knowing what the differences are and where they are (along with other data) allows us to predict the weather.

By the hot air going up and the cold weather going down